The Sony Ericsson S710a is a tri-band GSM phone available in the United States on the AT&T wireless network, formerly called the Cingular network. The SIM card, located behind the battery, locks the phone to a particular wireless carrier. Most S710a phones are locked to the AT&T network and programmed to reject SIM cards from other carriers. Each Sony Ericsson S710a has a unique code that, when entered at the appropriate menu, will unlock the phone and allow it to accept a SIM card from any GSM wireless provider.
Instructions
1. Slide the battery cover off of your S710a and lift the battery out of the phone. The battery cover is located on the back of the phone.
2. Contact AT&T customer service and request the unlock code for your S710a. You will need your phone's IMEI number, which can be found on the label behind the battery.
3. Slide the SIM card tray open. Remove the SIM card from your S710a and close the tray.
4. Install the battery and press the power button to turn on your S710a.
5. Press the "Left Arrow" key and then press the '*' key twice. Press the "Left Arrow" key once more.
6. Enter the unlock code at the "Personalize with MNC2" prompt that appears. Your S710a phone is now unlocked.
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